I had a similar problem when I got Dark Physics (not that I've used it much, so some of this info may be a bit vague). It could be that you need the latest PhysX Drivers, but i suspect you're trying to turn on hardware acceleration when you don't have a physX Processor to turn on.
It's not a problem, modern graphics cards are so good they don't really need a dedicated chip for physics, but you may not be able to do anything with fluids (except crash your computer, they take a LOT of processing power!)
Somewhere in each example is a command "Phy Start". You'll have to check the help files (Don't have a copy with me at the moment) for the numbers that follow this command, but one parameter is something like "Hardware mode", or "Hardware Acceleration". Make sure this is set to zero, i.e. off.
The programs should now run fine (Just watch out on the if/endif surrounding the Phy Start command, make sure you trigger the right thing). Hope this helps!
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